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JNBS
PROGRAMMING MANUAL
JNBS
Relative Jump if Bit Clear & Set Bit
Syntax
JNBS
Operation
IF (op1) = 0 THEN
(op1) = 1
(IP) <-- (IP) + sign_extend (op2)
ELSE
Next Instruction
END IF
Data Types
BIT
Description
If the bit specified by op1 is clear, program execution
continues at the location of the instruction pointer, IP, plus the
specified displacement, op2. The bit specified by op1 is set,
allowing implementation of semaphore operations. The
displacement is a two's complement number which is sign
extended and counts the relative distance in words. The
value of the IP used in the target address calculation is the
address of the instruction following the JNBS instruction. If
the specified bit was set, the instruction following the JNBS
instruction is executed.
op1, op2
Flags
Addressing Modes
104/197
1
E
Z
V
C
N
0
B
0
0
B
E
Always cleared.
Z
Contains logical negation of the previous state of
the specified bit.
V
Always cleared.
C
Always cleared.
N
Contains the previous state of the specified bit.
Mnemonic
JNBS
bitaddrQ.q, rel
Format
BA QQ rr q0
Bytes
4